This invention relates to a replaceable wear element and method and, more particularly, an element for installation on the wearable part of a structure engageable with abrasive material and a method of designing a dovetail connection therefor.
This invention is an improvement on co-owned U.S. Pat. No. RE 33,454. In that patent, a pair of spaced apart transversely-aligned, convergent dovetails were employed to provide a readily replaceable wear element--as for a cooperating base on the underside of an excavating bucket, scraper mold board, liner for an ore chute, or the like. The assembly of base and wear element was intended for installation in only one direction. This has not served the needs of operators in excavating, mining, etc. where reversibility is required.
It is also to be appreciated that the element subject to wear may have to be replaced frequently--many times the base element to which it is attached outlasting a multiple of wear elements.
According to the instant invention, reversibility is achieved through a novel arrangement of dovetail surfaces which makes possible the utilization, for example, of a single wear element where previously two different replacement elements had to be stored. For example, in the case of a bucket, it is advantageous to provide a wear element that wraps around a corner and thus, utilizing the patent teachings, it would be necessary to have both right and left hand styles. Now, through the practice of the invention, only a single, versatile replacement element is needed. This is a matter of some consequence to operators because buckets are usually employed in primitive conditions and storage facilities limited. Thus, anything that reduces the number of parts to be stored is highly desirable.
Further, the four dovetail surfaces required some care in manufacture to develop proper contact. Also, according to the instant invention, the novel arrangement of dovetail surfaces provides three-area contact. This results in stability, fit and installation advantages.
More particularly, the wear element has a pair of longitudinally aligned and longitudinally spaced apart dovetail surfaces and a transversely spaced third dovetail surface positioned between the spaced pair of dovetail surfaces. Also, one of the wear or base elements may have a second pair of longitudinally aligned and longitudinally spaced apart dovetail surfaces flanking the third surface and a single surface interposed between the pair of surfaces. This permits reversible mounting of the two pair-equipped element on the one pair-equipped element, both mountings being "three point" for advantageous ease, stability, etc.
Where "four point" contact is desired, each of the base and wear elements has first and second pairs of longitudinally spaced apart dovetail surfaces with one of the elements having third and fourth pairs of longitudinally spaced apart dovetail surfaces and with the dovetail surfaces of the third and fourth pairs being interlaced or intersperced with the dovetail surfaces of the first and second pairs. This permits reversible mounting of the four pair-equipped element on the two pair-equipped element.
The instant invention also teaches a method for designing the dovetail connection by developing a repeating pattern of dovetail surfaces in a pair of opposing walls and terminating the elements by transversely cutting by spaced transverse planes. Additional details of the invention can be seen in the ensuing specification.